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Acute Diarrheal Diseases
Equine Med + Sx
Terms in this set (30)
What is colitis?
Inflammation of colon
What is typhlitis?
Inflammation of cecum
What is typhlocolitis?
Inflammation of colon and cecum
What are some characteristics of acute diarrheal diseases of horses?
-Diarrhea very common issue in horses
-Prognosis varies with cause
-Diarrhea can be caused by anything that disrupts colonic bacteria (new feed, stress, etc)
-Common to have no diagnosis
-Isolate until infectious disease ruled out
What clinical signs are associated with colitis?
-Systemic inflammatory response syndrome (SIRS): toxic gum line, injected mm
-Increased, splashy gut sounds
-Dehydration leading to increased HR, skin tent, sunken eye
What are the typical CBC results of a horse with diarrhea?
WBC: initially low, then rebound increase
RBC indices: high due to dehydration
If horse has low blood protein, but is also dehydrated, may get normal protein; always look at protein compared to PCV and RBV #s
What are some typical serum chemistry abnormalities of horses with diarrhea?
-Low Na, Cl, Ca, K
-TCO2 low if acidemic
What are some other diagnostics done for a horse with diarrhea?
-Rectal exam: may feel splashy or liquid filled colons
-Abdominocentesis: rule out peritonitis
-Fecal culture + PCR
-Radiographs to visualize sand in large colon
Why is an ultrasound exam done for horses with acute diarrhea?
-Free fluid in abdomen
-Distended small intestine
-Gut wall thickness
How are acute diarrheal diseases of horses diagnosed and ruled out?
Diagnostic testing and history -
by clinical signs or clinical pathology data
What are some characteristics of salmonella?
-Gram negative facultative anaerobe rod
-Present in environment, shed in feces of other animals including asymptomatic horses
-Normal flora in birds + reptiles
What are the most common serotypes of salmonella?
What are the 2 general types of salmonella?
-Host adapted serovars
-Non host adapted
What are host adapted serovars?
-Normal gut flora in their hosts
-Rarely, if ever, cause severe disease in host
What are non-host adapted serovars?
Can be anywhere on spectrum from nonpathogenic to causing severe, fatal disease
What are some syndromes caused by salmonella?
Asymptomatic carriers 1-20% of population
-Acute enterocolitis +/- colic
-Colic +/- diarrhea, gastric reflux
-Chronic diarrhea, damaged gut wall
-Atypical salmonella; depression and fever, no diarrhea
-Septicemia in foals
What causes asymptomatic shedders to increase shedding?
-Use of stomach tube
What is the pathogenesis of salmonellosis dependent on?
-Host factors: age, immune status, drugs
-Bacteria factors: pathogenicity of ingested organism, dose of ingested organism
Salmonella must be attached to or within gut wall to cause disease
-Differences in pathogenicity relate to cellular factors in strain
What is the pathogenesis of salmonella once it reaches the intestine?
Attaches to enterocytes via fimbriae > can cause transient enterocyte degeneration > permits organism to penetrate intestinal cells > produces enterotoxin > disrupts Na, K, HCO3 balance > enteritis, diarrhea
What happens when salmonella is phagocytized by macrophages?
Not killed > reproduces in cells > eventually destroys cells > dissemination to other parts of body > gut wall > GI LN > liver > rest of body > endotoxin produced by lysed salmonella > endotoxic shock
How is salmonella diagnosed?
-Gold standard: isolate bacteria from feces
-Intermittent shedding or dilution effect from large volume of feces may make isolation difficult
-5 cultures needed to max. chances of isolation
-PCR of 3 or more consecutive fecal samples
-Can also culture biopsy materials from rectum
What post mortem diagnostics are done for salmonella?
-Culture GI LN, best place to isolate
-Tie off loop of affected intestine and submit contents for culture
-Look for changes consistent w/enteritis: discolored and necrotic bowel
What are some characteristics of PCR used for salmonella diagnosis?
-PCR of feces available for salmonella
-Poor correlation between PCR results and culture results when performing undifferentiated PCR on feces
-Good correlation when PCR run on material from selective media
How is salmonella treated?
-Heparin if DIC
-Plasma or hetastarch if TP low
-Encourage horse to eat high quality feeds and drink
-Want to establish and maintain normal gut flora
-Keep Na + Cl in normal range by offering electrolyte water and/or salt blocks (always offer fresh water too!)
How is colitis treated?
What are some characteristics of fluid therapy for colitis?
-Isotonic multi-electrolyte solutions probably best
-Hypertonic saline may be used initially to rapidly restore circulating fluid volume
-Maintenance adult 60 ml/kg/day
What are 3 factors that must be taken into account when calculating how much fluid to give a horse?
-Correct deficit (resuscitation)
What are another therapy used for acute diarrhea?
NSAIDs: flunixin meglumin drug of choice
Why are NSAIDs used for acute diarrheal disease?
-Decrease inflammation in gut wall and laminae
-May help w/prostaglandin mediated secretion
NSAID drugs reduce epithelial healing rate and may decrease healing times in cases of GI ulceration - discontinue ASAP once vital signs are back to normal
How is laminitis prevented?
-Control primary disease (#1)
-Ice on feet through cannon bones
-Frog support, deep bedding
-Prevention drugs: heparin, others
-Therapies which decrease blood pressure should NOT be given
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